This is an application for an ADAMHA RSA. The overall goal is to determine how psychological processes interact with physiology to influence the occurrence of physiological responses, the patient's perception that these physiological responses represent symptoms of disease, and his/her decision to seek health care. Studies are proposed in three areas: (1) Determinants of illness behavior. In Study I, multiple psychological variables (e.g. childhood social learning, personality traits, stress, depressed cognitions) will be tested concurrently to assess their relative contributions to somatization and health care utilization. In Study II, the validity of the diagnostic criteria for all functional gastrointestinal disorders recommended by an international commission will be tested by administering a symptom inventory to 2500 subjects and using factor analysis to identify (a) groups of symptoms which covary as syndromes and (b) symptom criteria which most reliably identify subjects with these syndromes. (2) Pain sensitivity in irritable bowel syndrome (IBS, defined by abdominal pain associated with altered bowel habits). In study I, the relationship between muscle tone, motility, and pain threshold will be studied in IBS patients and healthy controls. In study II, biopsies will be taken from areas of increased pain sensitivity and from control sites, and analyzed for cytokines and gastrointestinal peptides. In Study III, CNS influences on pain will be investigated by comparing IBS patients and controls with respect to sensitivity and response bias when discriminating between two intensities of painful stimulation in a signal detection paradigm. (3) Constipation in the Elderly. In study I, young and old clinic patients will be compared to determine which physiological subtypes of constipation are more common in the elderly. In Study II, the relationship of constipation to age, diet, exercise and psychological traits will be investigated in the Baltimore Longitudinal Study on Aging (1,035 participants stratified by age). Subjects who have not consulted physicians about their constipation will be matched to clinic patients to investigate how psychological traits influence health care utilization. In Study III, the effects of two types of exercise training, aerobic and strength training, on motility and transit in the distal colon will be studied in men aged 60 and older. In Study IV, biofeedback training to teach relaxation of the pelvic floor muscles will be compared to high fiber diet in the treatment of two types of constipation, pelvic floor dyssynergia and colonic inertia.